1. Field of the Invention
This invention concerns an orthopedic dental interocclusal appliance. More particularly, it concerns a dental splint for treating temporomandibular joint disorders and related problems.
2. General Discussion of the Background
An orthopedic interocclusal dental appliance is a removable splint, typically made of hard acrylic resin, that is placed between the maxillary (upper) and mandibular (lower) dental arches. Such an appliance has been found to stabilize and improve the function of the temporomandibular joint, which is the "hinge" about which the jaw moves. Such splints have also been found to improve the function of the muscles of mastication, reduce abnormal muscle activity, and protect teeth from traumatic grinding which often occurs in temporomandibular joint (TMJ) disorders.
Splint designs have been reviewed by Clark, Journal of the American Dental Association, 108:359-363 (1984); and Clark, Journal of the American Dental Association, 108:364-368 (1984). Methods of fabricating occlusal splints have also been described by Wright, Journal of the American Dental Association, 117:757-758 (1988). These splints typically cover the teeth of the lower dental arch and interdigitate with the teeth of the opposing upper arch. Such splints are manufactured by an indirect process in which the dentist takes an impression of the patient's teeth and makes a registration of the jaws in the desired therapeutic position. A splint is then indirectly manufactured in a laboratory from the impression and registration obtained by the dentist. The fabricated splint is typically returned to the dentist after a significant period of delay, and the splint is then placed in the patient's mouth.
There are several significant disadvantages with this indirect fabrication technique. One-serious drawback is that indirect fabrication usually requires at least several days to complete because the dentist must send the impression and registration to an outside laboratory. Unfortunately, patients with TMJ injury are often in serious pain and need a splint immediately, particularly after a traumatic joint injury. Any period of delay in placing the finished splint in the patient's mouth can cause unbearable pain during the period of delay.
Yet another disadvantage with indirect fabrication methods is that they increase the cost of the dental splint. Making impressions and sending them to a laboratory for conversion into a splint is costly. It multiplies the fabrication steps and increases the number of parties involved in the manufacturing chain. The expense associated with these multiple steps sometimes makes the splint more expensive than a patient can afford or an insurer is willing to pay.
Another disadvantage with indirect fabrication is that it is inaccurate. Bit registration must be very precise to be acceptable and helpful to patients. Unfortunately, a therapeutic bite constructed indirectly in the laboratory seldom fits perfectly in the patient's mouth. The indirectly fabricated splint must be adjusted by the dentist with the patient present. Such adjustments further increase the manufacturing expense and often result in a bite surface which is still not entirely accurate.
In view of the drawbacks of indirect fabrication techniques, attempts have also been made to fabricate splints directly in a patient's mouth. A method for constructing in situ a soft, interocculusal splint was disclosed by Hicks in The Journal of Prosthetic Dentistry, 61:48-50 (1989). A silicone rubber rope was placed on the mandibular teeth, and the patient's teeth were then closed on the rope to interdigitate with the rubber and form an impression. The impression remained stable once the silicone rubber set. The dental literature has recognized, however, that such silicone rubber splints cannot replace splints of hard plastic, but only supplement them. The silicone splints are used for less severe TMJ problems that respond in a few days, or are used in situations where patients need splints immediately.
Other attempts at in situ formation of dental splints have been made by placing a roll of soft acrylic directly over a patient's teeth and then having the patient bite into it. A problem with this technique is that acrylic fumes are extremely noxious and unpleasant. The large amount of acryl required in this method produces a high concentration of fumes that diminish patient comfort and compliance during fabrication. Splints made in this manner also have poor retention and easily dislodge from the teeth. Moreover, the resulting splint is thicker and more uncomfortable than one that has been made in the laboratory, which further diminishes patient compliance.
It is accordingly an object of this invention to provide an improved dental splint that can be fabricated directly in a patient's mouth.
It is yet another object of the invention to provide an improved dental splint that is comfortable, effective, and can be provided to the patient without significant delay.
Yet another object of the invention is to provide a splint having greater cost effectiveness than some of the other available dental splints.
Finally, it is an object of the invention to provide such an improved splint which is securely retained in position.
These and other objects of the invention will be understood more clearly by reference to the following detailed description and drawings.